"As of 09:00 a.m. today, some 200 were injured and 6 were killed," the Jakarta governor said in Tarakan hospital in central Jakarta.
He added that the killed ones are placed in central Jakarta's hospitals of Tarakan, Pelni, Budi Kemuliaan and Mintoharjo.
The clashes between police and protesters who rejected results of presidential election occurred in several spots in downtown central Jakarta area, near the election supervisory body (Bawaslu) building.
Police shot tear gas to disperse the groups of protesters who supported the defeated presidential candidate Prabowo Subianto. Some 20 protesters were arrested by police during the clashes, reports said.
Protesters burned down a police housing facility and several vehicles in KS Tubun Street in central Jakarta in the morning.
Jakarta Police Headquarters Spokesperson Argo Yuwono called on people to refrain from instantly trusting information that freely circulated in the social media related to the clash.
"What have been circulated in the social media give no benefit. You can cross check it with the police to find out whether the information is correct or not. People need to filter it first before use it as information," Argo said in his office on Wednesday.
Police have identified that the protesters involved in the clash with police were not residents of the capital city.
Police arrested five terrorist suspects in their operation held in West Java regency of Garut on Tuesday afternoon. They confiscated weapons from those suspects who rode a van to get to Jakarta.
More demonstrations are scheduled to be staged on Wednesday, consisted of several groups of Prabowo's supporters.
Indonesian authorities have closed down train stations near the demonstration areas, advising the passengers to board the train from other stations.
Prabowo has planned to lodge a lawsuit to the Constitutional Court related to results of real count carried out by General Elections Commission that puts incumbent President Joko Widodo as the winner of presidential election.